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[reaction: see text] We have developed, on the basis of a chelation-strategy, an efficient copper-catalyzed aziridination protocol with the use of 5-methyl-2-pyridinesulfonamide and PhI(OAc)(2). The reaction proceeds smoothly under mild conditions to give aziridines in moderate to good yields in the absence of external ligands or bases. The coordination-assisted approach offers the additional benefits that efficient deprotection of the N-substituent and selective aziridine ring-opening are effectively achieved.

Great attention has been paid to halide coordination chemistry, not only because it constitutes the fundamentals of inorganic chemistry, but because the versatile coordination abilities of halides can be used to construct many interesting polynuclear complexes, which include halidebridged inorganic polymers, halide-capped metal clusters, halide-templated polynuclear assemblies, and anionic guests. The structural versatility of halides mainly originates from their coordinating abilities of adopting a bridging bond between two or more metal atoms, as well as a terminal bond. Moreover, a halide bridging bond angle is so flexible that thermodynamic stability can be endowed with proper geometry, which conceptually varies from acute to right, obtuse, and linear. In spite of innumerable reports on molecular metal halides, examples of the linearly bridging fashion are very scarce. The reason for the rarity of the linear M–X–M arrangement can be easily explained by the VSEPR (Valence Shell Electron Pair Repulsion) concept. The linear M–X–M formation has only been achieved by adopting a macrocyclic chelate ligand, which is structurally demanding, so that the VSEPR repulsions among lone-pair electrons on the halide atom could be overcome. In the synthetic exploration of new cobaltacarboranes, we found an unexpected ionic product comprising a cation with a linear Ag–X–Ag arrangement. At first, we attempted a reaction between Tl2C2B9H11 and CoCl2(PPh3)2, mimicking the previously reported preparation of a nickellacarborane, [3,3-(PPh3)2–3,1,2–NiC2B9H11]. We found that a new cobalt complex of dicarbollide was generated, but no more information could be obtained. Treatment of the product mixture with AgBr(PPh3)3 afforded a cationic [L3Ag–X–AgL3] (L = triphenylphosphine) with CoSAN as a counterion (CoSAN = [3,3-commo-3,1,2-Co(C2B9H11)2]). Although linear Ag–X–Ag could be achieved, the reaction result was not well reproducible, nor was its mechanism reasonable. Hence, we directed the preparation of the linear complexes in a rationalized synthetic manner, as depicted in the following reaction equation

An ansa-zirconocene bearing methyl substituents at all positions adjacent to the bridgehead [(-C(Ph)HC(Ph)H-)(η(5)-2,5-Me2C5H2)2ZrCl2] (4) was prepared in high yields (78%) through the reductive dimerization of 1,4-dimethyl-6-phenylfulvene utilizing ZrCl2·DME generated in situ. The structure of 4 was subsequently confirmed using X-ray crystallography. 4 exhibited excellent catalytic performance with regard to 1-decene oligomerization, which was carried out with the intention of preparing lubricant base stocks. High activities (21 × 10(6) g mol(-1) Zr h(-1) activity; TON = 150 000; TOF = 42 s(-1)) were observed at temperatures as high as 120 °C and the oligomer distribution was appropriate for lubricant application. The simulated distillation (SIMDIS) data confirmed that a wide range of oligomers were formed, ranging from the dimer (2-mer) to 20-mer. A minimal amount of the dimer and oligomers larger than the 10-mer was formed (13 and 25 wt%, respectively). Alternatively, a typical unbridged complex such as (η(5)-nBuC5H4)2ZrCl2 primarily produced dimers (54 wt%), whereas the ansa-zirconocene (EBI)ZrCl2 primarily produced oligomers larger than 10-mer (62 wt%). The methyl substituents at the positions adjacent to the bridgehead in 4 played a significant role in the catalytic performance.

The title compound, C24H26O, was prepared by the reaction between 2-tert-butyl-4-methylphenol and diphenylmethanol in the presence of sulfuric acid. Three benzene rings are attached directly to the central C—H group in a twisted propeller conformation with the local pseudo-C3rotational axis coinciding with the C—H bond. There are three short C—H...O contacts in the molecule.

The asymmetric unit of the title hydrated salt, C18H40N4P(+)·Cl(-)·2H2O, consists of two ionic mol-ecules and four water mol-ecules. The mol-ecular geometry around the penta-coordinate P atom is trigonal-bipyramidal, with a H atom and an apical N atom in axial positions and three N atoms with isobutyl substituents in equatorial positions. The Cl(-) ions and water mol-ecules are connected via O-H⋯Cl hydrogen bonds, forming chains along [100]. The ethyl-ene bridging groups are disordered with refined site-occupancy ratios of 0.578 (9):0.422 (9).

This study experimentally shows the flight dynamics of a bioinspired ornithopter using two different types of approach: (1) free flight testing, and (2) wind tunnel testing. An ornithopter is flown in straight and level flight with a fixed wingbeat frequency and tail elevation angle. A three-dimensional visual tracking system is applied to follow the retro-reflective markers on the ornithopter and record the flight trajectories. The unique oscillatory behavior of the body in the longitudinal plane is observed in the free flight testing and the detailed wing and tail deformations are also obtained. Based on the trim flight data, a specially devised tether device is designed and employed to emulate the free flight conditions in the wind tunnel. The tether device provides minimal mechanical interference and longitudinal flight dynamic characteristics similar to those of free flight. On introducing a pitching moment disturbance to the body, the oscillation recovered to the original trajectory turns out to be a stable limit-cycle oscillation (LCO). During the wind tunnel testing, the magnitude of LCO is effectively suppressed by active tail motion.

The binuclear title complex, [Zn2(C22H28N3O)2(C3H9OSi)2], has a crystallographic imposed centre of symmetry. The ZnII atom is coordinated by three O and one N atom from one 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentyl­phenolate ligand and two bridging trimethyl­silanolate anions in a distorted tetra­hedral geometry. The dihedral angle between the benzotriazole ring system and the benzene ring is 19.83 (5)°. The tert-pentyl groups are disordered over two orientations with refined site-occupancy ratios of 0.858 (4):0.142 (4) and 0.665 (6):0.335 (6).

The dinuclear title complex, [Ti(2)(C(10)H(15))(2)(C(6)F(5)O)(4)O], features two Ti(IV) atoms bridged by an O atom, which lies on an inversion centre. The Ti(IV) atom is bonded to a η(5)-penta-methyl-cyclo-penta-dienyl ring, two penta-fluoro-phenolate anions and to the bridging O atom. The environment around the Ti(IV) atom can be considered as a distorted tetra-hedron. The cyclo-penta-dienyl ring is disordered over two sets of sites [site occupancy = 0.824 (8) for the major component].

Due to our editing mistake, Fig. 9a in Ref. [1] was wrongly used. The correct Fig. 9 is given in the right.